First few decades (or longer?) would be Hell on Earth. Compared to that, the time when the Fallout games are happening is a piece of cake - people are organized then and have learned to live in Postapocalyptia.

but the explotion in fallout happens in 1945 or 1950 and the story starts at 2077 it's along time, the towns and places was build from nothing and it takes a lot of time to construct civilization, the tows are from the people who lived in vaults, the others who born outside are raiders and super muitants